ML20037B289

Forwards IE Bulletin 77-02, Potential Failure Mechanism in Certain Westinghouse AR Relays W/Latch Attachments. Action Required

ML20037B289
Person / Time
Site:	Dresden, Byron, Braidwood, Quad Cities, Zion, LaSalle
Issue date:	09/12/1977
From:	James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
To:	Brian Lee COMMONWEALTH EDISON CO.
References
NUDOCS 8009100959
Download: ML20037B289 (1)

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1.2 1977 t..

Jocitet ilos.50-010, M-249, 50-254, 50-265, 50-295, 50-304, 50-373,

',r0-374, 50-451, 50-455, 50-455, 50-4,57 Corronvoalen P.dison Coapany NEII;: lir. Lyton Lde, Jr.

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',* ice Presidcut P.O. Bo:: ~/67 Chicago, IL 60f,90 Gentier on:

s Dicleccd in IE h11ctin lio. 77-02 sich rcquires at. tion by you uith regard to I

your power reactor facilit us.cica an operating license or c. construction pe n.d.t.

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1 SLould yoh have questions regarcing thic Lullotin or t m actic,ns reqdre.d of ycu, plea se contacc titio office.

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j, Sincercly, James G. itcppler Director i

Enclouure:

IE Bulletin 110. 77-02 cc.vfencl:

11. Ct.uro, Project Superintendent Gunnt.;r Sorenson, Site Project Superintendent B. Il. Stephenson, Station Supcrintendent' L. J. Duri.e, Site Project Superinten.1cnt

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September 12,'1977 IE Bulletin No. 77-02 POTENTIA 1. FAILURE MECl!ANISH IN CERTAIN WESTINCl!OUSE (W) AR RELAYS UlTl! LATCl! ATTACllMENTS Description of Circumstances:

r Westinghouse recently reported that a number of AR Relays, with a latch attachment to provide a scal-in feature, have failed during.

the system chech out of the Solid State Protection System (SSPS) at W Nuclear Instrumentation Control Division in Hunt Valley, Maryland.

Westinghouse has determined that contacts.of these AR Relays can reopen after the relay coil is de-energized even though the latch acchanism is engaged.

Normal operation calls for the contacts to remain closed sa that under abnormal conditions Safeguards actions, once initiated, go to completion.

The failure mechanism has been found to be caused by insufficient uanufacturing tolerances which prevent full travel of the relay contact assembly which is essential for proper relay operation.

This reduction of contact movement resulted from a design change

• nade in the relay contact assembly in mid 1973 by the W Control Products Division, Beaver, Pennsylvania.

In addition to the tole-rance problem, it was determined that excessive tightening of the contact cartridge terminal screw may also contribute to the malfunction of the contacts during relay, operation where tolerances are marginal. AR Relays using latch attachments and produced prior to mid 1973 are not a matter of concern in this issue.

The enclosed W Technical Bulletin, NSD TB 77-10 was sent to all affected Westinghouse plants notifying them cf the problem and of the corrective actions being taken. The technical bulletin describes in detail the action developed by W to correct the identi-ficd problum.

The tcchnical bulletin also provides specific virjng instructions to assure that design tolerances are not reduced by c::cessive tightening of electrical terminals on the relay.

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lE Bulletin No. 77-02

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September 12, 1977 Action Lo Be Taken By Licensces and Permit iloiders:

For all power reactor facilities with an operating ifcense or a construction permit:

,1)

Describe what action you have taken to determine whether the

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relays of the type and vintage described in the enclosed W Bulletin are in use or planned for use in safety related systems at your facility.

(2)

Describe what action you plan to take regarding replacement of any relays of the type and vintage described uhich are in use or planned for use in safety related systems.

Further instruction pertaining to replacement. procedures can bc

'obtained from the W Nuclear Service Department in Monroeville, Peansylvania.

(3)

Report to this office in writing within 45 days for facilitics with an operating license and within 60 days for f acilitics with a construction permit, the results of findings with reg.a:d to Item 1 or 2.

Approval of NRC requirements for reperts concerning possible gener'c i

problems has been obtained from the U. S. General Accounting Office.

(GAO approval B-180225 (R0072) expires 7/31/80).

Enclosures:

1.

Extract From W Technical Bulletin NSD-77-10 Entitled "AR Relays with Latch Attachment" 2.

List of IE Bulletins issued in 1977 I

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COPY (Extracted from W Techhical Bulletin NSD TB 77-10)

Subject:

AR RELAYS WITH LATC11 ATTACl!MENTS s

Number:

NSD-TB-77-10 System (s) :

Solid State Protection System (SSPS) and Auxiliary Scfcguards Cabinets (ASC)

Date:

July 21, 1977 Affected Plants: See following S.O.(c) 385

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BACKGROUND INFORMATION Westinghouse has recently experienced an increase in the number of failures of AR Relays with latch attachments during the SSPS system checL-out at the supplier's (UNICD) shop. Discussicas with UNICO and W Control Products Division (AR Relay supplier) on this subject identified that a design change was made in the contact cartridge assembly which may have compromised the operability and reliability of the AR relay with latch attachment assembly.

This change was implemented in mid 1973 at W Control Products Division.

Specifically, the design change reduced the thickness of the moveable contact button which, in turn, reduced contact overtravel.

In addi-tion, it was also determined that overtightening of the contact cartridge terminal screw, which also acts as the cartridge holding screw, may ~ deform the stationary contact assembly, further reducing contact overtravel. Once the relay is de-energiscd, the latch plunger back-travels to engage its mechanical stop.

It is this acticn.

which al, lows the contacts to relax a distance approaching or c::cceding that of the contact overtravel.

The end effect is that on AR relays with latch attachments, contact continuity could be lost after the actuation coil has been de-energized even though the latch mechanism is working properly.

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COPY The above dealan change was made in mid 1973 and suspect relays can be identified by both:

1.

Manufaccures code date - (located on underside of relay base which can be viewed only by removing the relay).

Decode as follows: S-1.

U-2, I-3, T=4, C=5,11=6, G=7, E=8, A=9, R=0 (E:: ample - GGI=7/73) 2.

Removing each contcet cartridge: The moveable contact area vill be round add-on button (A square, integral moveabic assembly is the Bood pre-change style).

REC 021 ENDED ACTION A.

The following plants are to notify WNSD if they have replaced any original equipment relays with latches, or have added any relays with latches that have been identified as being made af ter 6/73

(!!GI) and have the round, add-on contact button.

Should any doubt exist as to this status, all AR relays with latches must be identified per the method'above.

Operating plants may postpone this action until a reasonable opportunity exists (i.e. shutdown),

since this design deficiency is detectable during periodic safe-guards testing.

In any event, replacement parts will be made available as soon as they are qualified.

1. Solid State Protection System:

OHI #1 Salem #1 & #2 North Anaa #1 & #2 Ringhris #2 D.C. Cook #1 & #2 Sequoyah 61 & #2 Joseph Farley #1 Beaver Valley #1

2. Auxiliary Safeguards Cabinet:

D.C. Cook #1 Beaver Valley #1 B.

The following plants will have contact cartridges available to them '

by the latter part of 1977 as replacements for all AR relays with latch attachments. Therefore, no customer action is required at this time.

1.

Solid State Protection System: William McGuire #1 & #2 Braidwood fi & #2 OHI #2 Ringhals #3 & Ft Joseph Farley #2 Beaver Valley F2 Watts Bar #1 6 #2 Marble Hill #1 5 Almaras #1 6 #2 Millstone #3 Virgil C. Sum =cr KRSKO Lemonia #1 Catawba #1 & #2 ASCO #1 Commanche Peak 11 Byron #1 & #2 Enclosure I

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2. Au::111ary Safeguards Cabinct1 Williar. McGuire #1 & #2 Byron 41 L- #2 0111 # 1 & # 2 Israidwood #1 & #2 Joseph Farley #1 & #2 Ecaver Valley #2 Almaraz #1 & 12 Angra #1 Virgil C. Sumer D. C. Cook //2 Lemonic #1 & #2 North Anna #1 & #2 C.

On all future applications of AR relays with latch attachments, use f-only the approved contact cartridge that will result from the resolu-tion of this prob 1cm.

Once qualified, it will have a unique identification code.

D.

Upon installation of any contact cartridge, new or existing, or the clianging of any wire terminations to any AR relay, the maximum torque applied to the termine.1 screws chall not exceed 10 inch-pounds.

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LISTIllG Or IE BULLETII!S ISSUED IN 1977 Eulletin-Subject First Date Issued Issued To

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No.

7-01 Pneumatic Time 4-29-7~

All., Holders of Drift Operating Licer.se Delay Set Point (OL) or Construc-tion Permit (CP) 1 Page 1 of 1 9

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